Interphotoreceptor Retinoid-binding Protein Peptide Research Articles

Antigen-Specific Intraocular Cytokine Responses Distinguish Ocular Tuberculosis From Undifferentiated Uveitis in Tuberculosis-Immunoreactive Patients

To compare antigen-specific intraocular immune responses between different clinical phenotypes of tuberculin skin test (TST)-positive and TST-negative uveitis. Single center, retrospective cross-sectional study. Patients requiring diagnostic or therapeutic vitrectomy for the management of intraocular inflammation were divided into 3 groups based on Standardization of Uveitis Nomenclature (SUN) classification criteria for tubercular uveitis. Group 1 included patients with ocular tuberculosis (OTB; n=23) who were TST-positive patients, met the SUN criteria, and/or had a polymerase chain reaction (PCR)-positive test for TB. Group 2 included patients with uveitis of unknown origin (UNK; n=24) who were undifferentiated TST-positive patients who had not met SUN criteria. Group 3 included non-TB uveitis patients (n=24) who were TST-negative either with or without a well-defined non-TB diagnosis. Total vitreous cells were activated with Mycobacterium tuberculosis-specific Early Secreted Antigenic Target-6 (ESAT-6) or the retinal autoantigen, interphotoreceptor retinoid-binding protein peptide (pIRBP 1-20), stained forintracellular interferon gamma (IFNγ), tumor necrosis factor-alfa (TNFα), and interleukin 17 (IL-17), and analyzed by flow cytometry. Antigen-specific single and dual (polyfunctional) cytokine responses to ESAT-6 and IRBP were compared between the 3 groups. All cytokine responses to ESAT-6 were higher in the UNK group compared with the non-TB control subjects, while all except IL-17 were comparable between the OTB and non-TB groups. Polyfunctional responses-IFNγ/IL-17 (P=.002), TNFα/IL-17 (P=.02), and TNFα/IFNγ (P=.01)-were significantly greater for UNK than the OTB group. Polyfunctional cells also produced more cytokine per cell than respective monofunctional cells. IRBP cytokine responses were comparable between different groups and were not affected by the clinical phenotype or duration of disease. The intraocular polyfunctional cytokine response is stronger in undifferentiated TST-positive uveitis than in OTB patients, likely representing an exaggerated anti-TB immune response rather than active infection.

CD47 Binding on Vascular Endothelial Cells Inhibits IL-17-Mediated Leukocyte Adhesion.

To address the conflicting role of thrombospondin (TSP)-1 reported in acute and chronic pathologies, this study investigated the role of TSP-1 in regulating leukocyte recruitment and regulation of VCAM-1 expression using mouse models of uveitis. The spontaneously increased VCAM-1 expression and leukocyte adhesion in retinas of TSP-1-deficient mice suggested a TSP-1-mediated regulation of VCAM-1 expression. In a chronic uveitis model, induced by immunizing wild-type mice with specific interphotoreceptor retinoid-binding protein (IRBP) peptide, topically applied TSP-1-derived CD47-binding peptide significantly reduced the clinical disease course and retinal leukocyte adhesion as compared to the control peptide-treated group. In contrast, in LPS-mediated acute uveitis, TSP-1 deficiency significantly reduced the retinal leukocyte adhesion. The results of our in vitro study, using vascular endothelial cell (EC) cultures, demonstrate that unlike TNF-α, VCAM-1 expression induced by IL-17 is associated with a reduced expression of endogenous TSP-1. Such reduced endogenous TSP-1 expression in IL-17-stimulated ECs helps limit the CD36-mediated increased VCAM-1 expression, while favoring CD47-mediated inhibition of VCAM-1 expression and leukocyte adhesion. Thus, our study identifies TSP-1:CD47 interaction as a molecular pathway that modulates IL-17-mediated VCAM-1 expression, contributing to its anti-inflammatory effect in chronic inflammatory conditions.

The innate immune receptor Nlrp12 suppresses autoimmunity to the retina

BackgroundNod-like receptors (NLRs) are critical to innate immune activation and induction of adaptive T cell responses. Yet, their role in autoinflammatory diseases of the central nervous system (CNS) remains incompletely defined. The NLR, Nlrp12, has been reported to both inhibit and promote neuroinflammation in an animal model of multiple sclerosis (experimental autoimmune encephalomyelitis, EAE), where its T cell-specific role has been investigated. Uveitis resulting from autoimmunity of the neuroretina, an extension of the CNS, involves a breach in immune privilege and entry of T cells into the eye. Here, we examined the contribution of Nlrp12 in a T cell-mediated model of uveitis, experimental autoimmune uveitis (EAU).MethodsMice were immunized with interphotoreceptor retinoid-binding protein peptide 1–20 (IRBP1–20) emulsified in Complete Freund’s adjuvant, CFA. Uveitis was evaluated by clinical and histopathological scoring, and comparisons were made in WT vs. Nlrp12−/− mice, lymphopenic Rag1−/− mice reconstituted with WT vs. Nlrp12−/− CD4+ T cells, or among bone marrow (BM) chimeric mice. Antigen-specific Th-effector responses were evaluated by ELISA and intracellular cytokine staining. Cellular composition of uveitic eyes from WT or Nlrp12−/− mice was compared using flow cytometry. Expression of Nlrp12 and of cytokines/chemokines within the neuroretina was evaluated by immunoblotting and quantitative PCR.ResultsNlrp12−/− mice developed exacerbated uveitis characterized by extensive vasculitis, chorioretinal infiltrates and photoreceptor damage. Nlrp12 was dispensable for T cell priming and differentiation of peripheral Th1 or Th17 cells, and uveitis in immunodeficient mice reconstituted with either Nlrp12−/− or WT T cells was similar. Collectively, this ruled out T cells as the source of Nlrp12-mediated protection to EAU. Uveitic Nlrp12−/− eyes had more pronounced myeloid cell accumulation than uveitic WT eyes. Transplantation of Nlrp12−/− BM resulted in increased susceptibility to EAU regardless of host genotype, but interestingly, a non-hematopoietic origin for Nlrp12 function was also observed. Indeed, Nlrp12 was found to be constitutively expressed in the neuroretina, where it suppressed chemokine/cytokine induction.ConclusionsOur data identify a combinatorial role for Nlrp12 in dampening autoimmunity of the neuroretina. These findings could provide a pathway for development of therapies for uveitis and potentially other autoinflammatory/autoimmune diseases of the CNS.

Overexpressing Kallistatin Aggravates Experimental Autoimmune Uveitis Through Promoting Th17 Differentiation.

Kallistatin or kallikrein-binding protein (KBP) has been reported to regulate angiogenesis, inflammation and tumor progression. Autoimmune uveitis is a common, sight-threatening inflammatory intraocular disease. However, the roles of kallistatin in autoimmunity and autoreactive T cells are poorly investigated. Compared to non-uveitis controls, we found that plasma levels of kallistatin were significantly upregulated in patients with Vogt-Koyanagi-Harada (VKH) disease, one of the non-infectious uveitis. Using an experimental autoimmune uveitis (EAU) model induced by human interphotoreceptor retinoid-binding protein peptide 651-670 (hIRBP651-670), we examined the effects of kallistatin on the pathogenesis of autoimmune diseases. Compared to wild type (WT) mice, kallistatin transgenic (KS) mice developed severe uveitis with dominant Th17 infiltrates in the eye. In addition, the proliferative antigen-specific T cells isolated from KS EAU mice produced increased levels of IL-17A, but not IFN-γ or IL-10 cytokines. Moreover, splenic CD4+ T cells from naïve KS mice expressed higher levels of Il17a mRNA compared to WT naïve mice. Under Th17 polarization conditions, KS mice exhibited enhanced differentiation of naïve CD4+ T cells into Th17 cells compared to WT controls. Together, our results indicate that kallistatin promotes Th17 differentiation and is a key regulator of aggravating autoinflammation in EAU. Targeting kallistatin might be a potential to treat autoimmune disease.

Macrophage-like iPS-derived Suppressor Cells Reduce Th1-mediated Immune Response to a Retinal Antigen

ABSTRACT Purpose To investigate the immunotherapeutic effects of macrophage-like induced pluripotent stem (iPS) cell-derived suppressor cells (SCs) in ocular immune response and experimental autoimmune uveoretinitis (EAU). Methods The genes of Oct3/4, Sox2, Klf4, and c-Myc were transferred to B cells enriched from the spleen cells of C57BL/6 mice by using retrovirus vectors. Transferred B cells were cultured for 17 days to obtain colonies of iPS cells. Through additional steps, iPS-SCs were induced. An antigen-specific T cell proliferation assay was performed with CD4+ T cells collected from draining lymph nodes of the mice immunized with human interphotoreceptor retinoid-binding protein (hIRBP) peptide and co-cultured with iPS-SCs. Cytokine concentrations in the culture supernatant were examined. Mice were immunized with hIRBP peptide to induce EAU. The iPS-SCs were administered into the mice one day before the induction of EAU. Results The iPS-SCs decreased hIRBP-specific T cell proliferation depending on the number of cells. Productions of tumor necrosis factor-α and interferon-γ were significantly decreased; however, transforming growth factor-β1, nitric oxide, interleukin (IL)-13, IL-17A, and IL-17 F levels were elevated in the supernatant when the collected T cells were co-cultured with iPS-SCs. The iPS-SCs had immunosuppressant effects even without cell-to-cell contact, and their effects were non-specific to the antigen preloaded on iPS-SCs. EAU was significantly milder in the mice administered iPS-SCs prior to immunization. Conclusions Macrophage-like iPS-SCs reduced Th1 immune response to a retinal antigen and Th1-mediated EAU in mice. These results showed the possibility of the application of iPS technology to the treatment of noninfectious ocular inflammation, endogenous uveitis, in the future.

High Ambient Temperature Aggravates Experimental Autoimmune Uveitis Symptoms.

Whether ambient temperature influences immune responses leading to uveitis is unknown. We thus tested whether ambient temperature affects the symptoms of experimental autoimmune uveitis (EAU) in mice and investigated possible mechanisms. C57BL/6 mice were kept at a normal (22°C) or high temperature (30°C) housing conditions for 2 weeks and were then immunized with human interphotoreceptor retinoid-binding protein (IRBP651–670) peptide to induce EAU. Histological changes were monitored to evaluate the severity of uveitis. Frequency of Th1 cells and Th17 cells was measured by flow cytometry (FCM). The expression of IFN-γ and IL-17A mRNA was measured by real-time qPCR. The generation of neutrophil extracellular traps (NETs) was quantified by enzyme-linked immunosorbent assay (ELISA). Differential metabolites in the plasma of the mice kept in the aforementioned two ambient temperatures were measured via ultra-high-performance liquid chromatography triple quadrupole mass spectrometry quadrupole time of flight mass spectrometry (UHPLC-QQQ/MS). The differential metabolites identified were used to evaluate their effects on differentiation of Th1 and Th17 cells and generation of NETs in vitro. The results showed that EAU mice kept at high temperature experienced a more severe histopathological manifestation of uveitis than mice kept at a normal temperature. A significantly increased frequency of Th1 and Th17 cells in association with an upregulated expression of IFN-γ and IL-17A mRNA was observed in the splenic lymphocytes and retinas of EAU mice in high temperature. The expression of NETs as evidenced by myeloperoxidase (MPO) and neutrophil elastase (NE), was significantly elevated in serum and supernatants of neutrophils from EAU mice kept at high temperature compared to the normal temperature group. The metabolites in the plasma from EAU mice, fumaric acid and succinic acid, were markedly increased in the high temperature group and could induce the generation of NETs via the NADPH oxidase-dependent pathway, but did not influence the frequency of Th1 and Th17 cells. Our findings suggest that an increased ambient temperature is a risk factor for the development of uveitis. This is associated with the induction of Th1 and Th17 cells as well as the generation of NETs which could be mediated by the NADPH oxidase-dependent pathway.

Small-molecule antagonist of VLA-4 (GW559090) attenuated neuro-inflammation by targeting Th17 cell trafficking across the blood-retinal barrier in experimental autoimmune uveitis

BackgroundThe integrin VLA-4 (α4β1) plays an important role in leukocyte trafficking. This study investigated the efficacy of a novel topical α4β1 integrin inhibitor (GW559090, GW) in a mouse model for non-infectious posterior uveitis (experimental autoimmune uveitis; EAU) and its effect on intraocular leukocyte subsets.MethodsMice (female; B10.RIII or C57Bl/6; aged 6–8 weeks) were immunized with specific interphotoreceptor retinoid-binding protein (IRBP) peptides to induce EAU. Topically administered GW (3, 10, and 30 mg/ml) were given twice daily either therapeutically once disease was evident, or prophylactically, and compared with vehicle-treated (Veh) and 0.1% dexamethasone-treated (Dex) controls. Mice were sacrificed at peak disease. The retinal T cell subsets were investigated by immunohistochemistry and immunofluorescence staining. The immune cells within the retina, blood, and draining lymph nodes (dLNs) were phenotyped by flow cytometry. The effect of GW559090 on non-adherent, adherent, and migrated CD4+ T cell subsets across a central nervous system (CNS) endothelium was further assayed in vitro and quantitated by flow cytometry.ResultsThere was a significant reduction in clinical and histological scores in GW10- and Dex-treated groups as compared to controls either administered therapeutically or prophylactically. There were fewer CD45+ leukocytes infiltrating the retinae and vitreous fluids in the treated GW10 group (P < 0.05). Immunofluorescence staining and flow cytometry data identified decreased levels of retinal Th17 cells (P ≤ 0.001) in the GW10-treated eyes, leaving systemic T cell subsets unaffected. In addition, fewer Ly6C+ inflammatory monocyte/macrophages (P = 0.002) and dendritic cells (P = 0.017) crossed the BRB following GW10 treatment. In vitro migration assays confirmed that Th17 cells were selectively suppressed by GW559090 in adhering to endothelial monolayers.ConclusionsThis α4β1 integrin inhibitor may exert a modulatory effect in EAU progression by selectively blocking Th17 cell migration across the blood-retinal barrier without affecting systemic CD4+ T cell subsets. Local α4β1 integrin-directed inhibition could be clinically relevant in treating a Th17-dominant form of uveitis.

Regulated Tristetraprolin Overexpression Dampens the Development and Pathogenesis of Experimental Autoimmune Uveitis.

Non-infectious uveitis, a common cause of blindness in man, is often mediated by autoimmunity, a process in which cytokines play major roles. The biosynthesis and secretion of pro-inflammatory cytokines are regulated in part by tristetraprolin (TTP), an endogenous anti-inflammatory protein that acts by binding directly to specific sequence motifs in the 3’-untranslated regions of target mRNAs, promoting their turnover, and inhibiting synthesis of their encoded proteins. We recently developed a TTP-overexpressing mouse (TTPΔARE) by deleting an AU-rich element (ARE) instability motif from the TTP mRNA, resulting in increased accumulation of TTP mRNA and protein throughout the animal. Here, we show that homozygous TTPΔARE mice are resistant to the induction of experimental autoimmune uveitis (EAU) induced by interphotoreceptor retinoid-binding protein (IRBP), an established model for human autoimmune (noninfectious) uveitis. Lymphocytes from TTPΔARE mice produced lower levels of the pro-inflammatory cytokines IFN-γ, IL-17, IL-6, and TNFα than wild type (WT) mice. TTPΔARE mice also produced lower titers of antibodies against the uveitogenic protein. In contrast, TTPΔARE mice produced higher levels of the anti-inflammatory cytokine IL-10, and had higher frequencies of regulatory T-cells, which, moreover, displayed a moderately higher per-cell regulatory ability. Heterozygous mice developed EAU and associated immunological responses at levels intermediate between homozygous TTPΔARE mice and WT controls. TTPΔARE mice were able, however, to develop EAU following adoptive transfer of activated WT T-cells specific to IRBP peptide 651–670, and naïve T-cells from TTPΔARE mice could be activated by antibodies to CD3/CD28. Importantly, TTPΔARE antigen presenting cells were significantly less efficient compared to WT in priming naïve T cells, suggesting that this feature plays a major role in the dampened immune responses of the TTPΔARE mice. Our observations demonstrate that elevated systemic levels of TTP can inhibit the pathogenic processes involved in EAU, and suggest the possible use of TTP-based treatments in humans with uveitis and other autoimmune conditions.

Chitosan Oligosaccharides Suppress Nuclear Factor-Kappa B Activation and Ameliorate Experimental Autoimmune Uveoretinitis in Mice.

We investigated the therapeutic potential and mechanism of chitosan oligosaccharides (COS) for experimental autoimmune uveoretinitis (EAU) in mice. EAU was induced in C57/BL6 mice by injection of human interphotoreceptor retinoid-binding protein (IRBP) peptides. At the same time, a high or low dose (20 or 10 mg/kg) of COS or phosphate-buffered saline (PBS) was given to mice daily after EAU induction. We found that mouse EAU is ameliorated by the high-dose COS treatment when compared with PBS treatment. In the retinas of high-dose COS-treated mice, the nuclear translocation of NF-κB subunit (p65) was suppressed, and the expression of several key EAU inflammatory mediators, IFN-γ, TNF-α, IL-1α, IL-4, IL-5, IL-6, IL-10, IL-17 and MCP-1 was lowered. These results suggest that COS may be a potential treatment for posterior uveitis.

Characterization of Clinical and Immune Responses in an Experimental Chronic Autoimmune Uveitis Model

Autoimmune uveitis is a sight-threatening intraocular inflammatory disease. For >30 years, the mouse model of experimental autoimmune uveitis has been employed to investigate disease mechanisms and test immunotherapeutic approaches. However, inflammation in this model is self-limited, and does not replicate the chronic, insidious nature prevalent in the human disease. Herein, a robust and reliable model of chronic autoimmune uveitis was developed and characterized in two strains of wild-type mice by modifying interphotoreceptor retinoid-binding protein dose and peptide fragments from conventional experimental autoimmune uveitis models. In both of these murine strains, immunization with our modified protocols resulted in a slowly progressive uveitis, with retinal scars and atrophy observed in the chronic stage by fundoscopy. Optical coherence tomography demonstrated decreased retinal thickness in chronic autoimmune uveitis mice, and electroretinography showed significantly reduced amplitudes of dark-adapted a- and b-waves and light-adapted b-waves. Histologic examination revealed prominent choroiditis with extensive retinal damage. Flow cytometry analysis showed substantially increased numbers of CD44hiIL-17+IFN-γ- memory T-helper 17 (Th17) cells in the retina, cervical lymph nodes, inguinal lymph nodes, and spleen. These data establish new modified protocols for inducing chronic uveitis in wild-type mice, and demonstrate a predominant memory Th17 cell response, suggesting an important role for memory Th17 cells in driving chronic inflammation in autoimmune uveitis.

Effect of In Vivo Expansion of Regulatory T Cells with IL-2/anti-IL-2 Antibody Complex Plus Rapamycin on Experimental Autoimmune Uveoretinitis

ABSTRACT Purpose: To determine the effect of injection of IL-2/anti-IL-2 antibody (IL-2 complex) together with rapamycin on the development of experimental autoimmune uveoretinitis (EAU). Methods: C57BL/6J mice were immunized with human interphotoreceptor retinoid-binding protein peptide. The immunized mice were injected intraperitoneally with PBS, IL-2 complex, rapamycin, or IL-2 complex/rapamycin on days 1, 2, 3, and 4 (induction phase) or days 10, 11, 12, and 13 (effector phase) after immunization. Results: Expansion of CD4+Foxp3+ regulatory T cells in draining lymph nodes was observed in IL-2 complex and IL-2 complex/rapamycin-treated mice. Although injection of IL-2 complex alone was not capable of decreasing the clinical score of EAU, injection of IL-2 complex/rapamycin significantly delayed the onset of EAU. In contrast, the treatment with IL-2 complex alone or IL-2 complex/rapamycin during effector phase failed to suppress EAU. Conclusions: These findings suggest the potential limitations of IL-2 complex or IL-2 complex/rapamycin during EAU.

Aminooxy-Acetic Acid Inhibits Experimental Autoimmune Uveitis by Modulating the Balance between Effector and Regulatory Lymphocyte Subsets.

A small molecular compound, aminooxy-acetic acid (AOA), has been shown to modulate experimental autoimmune encephalomyelitis (EAE). The current study was designed to investigate whether AOA has a similar effect on the development of experimental autoimmune uveitis (EAU) and to further explore underlying mechanisms of this drug. EAU was induced in C57BL/6J mice by immunization with interphotoreceptor retinoid-binding protein peptide 651-670 (IRBP 651-670). AOA (500μg or 750μg) or vehicle was administered by intraperitoneal injection from day 10 to 14 after EAU induction. The severity was assessed by clinical and histological scores. The integrity of the blood retinal barrier was detected with Evans Blue. Frequencies of splenic Th1, Th17 and Foxp3+ Treg cells were examined by flow cytometry. The production of cytokines was tested by ELISA. The mRNA expression of IL-17, IFN-γ and IL-10 was detected by RT-PCR. The expression of p-Stat1 and NF-κB was detected by Western Blotting. AOA was found to markedly inhibit the severity of EAU, as determined by clinical and histopathological examinations. AOA can relieve the leakage of blood retinal barrier (BRB). Functional studies found a decreased frequency of Th1 and Th17 cells and an increased frequency of Treg cells in EAU mice as compared with controls. Further studies showed that AOA not only downregulated the production of the proinflammatory cytokines including IFN-γ and IL-17 but also upregulated the expression of an anti-inflammatory cytokine such as IL-10, which might be caused by inhibiting the expressions of p-Stat1 and NF-κB. This study shows that AOA inhibits the severity and development of EAU by modulating the balance between regulatory and pathogenic lymphocyte subsets.

Dendritic cells mediate the anti-inflammatory action of omega-3 long-chain polyunsaturated fatty acids in experimental autoimmune uveitis.

We previously showed that dietary omega (ω)–3 long-chain polyunsaturated fatty acids (LCPUFAs) suppress inflammation in mice with experimental autoimmune uveitis (EAU). We have now investigated the role of antigen presenting cells (APCs) in this action of ω-3 LCPUFAs. C57BL/6 mice were fed a diet supplemented with ω-3 or ω-6 LCPUFAs for 2 weeks, after which splenocytes were isolated from the mice and cocultured with CD4+ T cells isolated from mice with EAU induced by injection of a human interphotoreceptor retinoid-binding protein peptide together with complete Freund’s adjuvant. The proliferation of and production of interferon-γ and interleukin-17 by T cells from EAU mice in vitro were attenuated in the presence of splenocytes from ω-3 LCPUFA–fed mice as compared with those from mice fed ω-6 LCPUFAs. Splenocyte fractionation by magnetic-activated cell sorting revealed that, among APCs, dendritic cells (DCs) were the target of ω-3 LCPUFAs. Adoptive transfer of DCs from mice fed ω-3 LCPUFAs attenuated disease progression in EAU mice as well as the production of pro-inflammatory cytokines by T cells isolated from these latter animals. The proliferation of T cells from control Balb/c mice was also attenuated in the presence of DCs from ω-3 LCPUFA–fed mice as compared with those from ω-6 LCPUFA–fed mice. Furthermore, T cell proliferation in such a mixed lymphocyte reaction was inhibited by prior exposure of DCs from mice fed an ω-6 LCPUFA diet to ω-3 LCPUFAs in vitro. Our results thus suggest that DCs mediate the anti-inflammatory action of dietary ω-3 LCPUFAs in EAU.

Disruption of Intestinal Homeostasis and Intestinal Microbiota During Experimental Autoimmune Uveitis.

PurposeWe determine the changes in intestinal microbiota and/or disruptions in intestinal homeostasis during uveitis.MethodsExperimental autoimmune uveitis (EAU) was induced in B10.RIII mice with coadministration of interphotoreceptor retinoid-binding protein peptide (IRBP) and killed mycobacterial antigen (MTB) as an adjuvant. Using 16S rRNA gene sequencing, we looked at intestinal microbial differences during the course of uveitis, as well as intestinal morphologic changes, changes in intestinal permeability by FITC-dextran leakage, antimicrobial peptide expression in the gastrointstinal tract, and T lymphocyte prevalence before and at peak intraocular inflammation.ResultsWe demonstrate that increased intestinal permeability and antimicrobial peptide expression in the intestinal tract coincide in timing with increased effector T cells in the mesenteric lymph nodes, during the early stages of uveitis, before peak inflammation. Morphologic changes in the intestine were most prominent during this phase, but also occurred with adjuvant MTB alone, whereas increased intestinal permeability was found only in IRBP-immunized mice that develop uveitis. We also demonstrate that the intestinal microbiota were altered during the course of uveitis, and that some of these changes are specific to uveitic animals, whereas others are influenced by adjuvant MTB alone. Intestinal permeability peaked at 2 weeks, coincident with an increase in intestinal bacterial strain differences, peak lipocalin production, and peak uveitis.ConclusionsAn intestinal dysbiosis accompanies a disruption in intestinal homeostasis in autoimmune uveitis, although adjuvant MTB alone promotes intestinal disruption as well. This may indicate a novel axis for future therapeutic targeting experimentally or clinically.

Crucial role of P2X7 receptor for effector T cell activation in experimental autoimmune uveitis.

To investigate the roles of P2X7 receptors (P2RX7) in the pathogenesis of experimental autoimmune uveoretinitis (EAU). Experimental. Either wild-type (P2rx7 +/+ ) or P2rx7-deficient (P2rx7 -∕- ) mice were immunized with interphotoreceptor retinoid-binding protein (IRBP) peptide 1-20. Severity of EAU was evaluated clinically and histopathologically. The induction of IRBP-specific proliferation and cytokines in draining lymph nodes was assessed by enzyme-linked immunosorbent assays (ELISA). The frequency of activation markers was examined by flow cytometry. Furthermore, inhibitory roles of systemic administration of Brilliant Blue G (BBG), an antagonist for P2RX7, in EAU were also assessed in the wild-type mice. The severity of EAU in P2rx7 -∕- mice was reduced as compared with that in P2rx7 +/+ mice, both clinically and histopathologically. IRBP-specific proliferation in P2rx7 -∕- on day 16 was slightly decreased compared to that in P2rx7 +/+ mice. The induction of IRBP-specific interferon (IFN)-γ and interleukin (IL)-17 in P2rx7 -∕- mice on day 16 was lower than that in P2rx7 +/+ mice. The up-regulation of surface expression of activation markers such as CD25, CD44, and CD69 in response to TCR stimulation in P2rx7 -∕- mice was decreased as compared with that in P2rx7 +/+ mice. Furthermore, neutralization of P2RX7 in vivo by BBG suppressed EAU clinically and histopathologically. IRBP-specific IFN-γ and IL-17 induction in BBG-treated mice was significantly lower than that in vehicle-treated mice. The results suggest that P2RX7 is a novel preventative therapeutic target for uveitis as it suppresses the effector functions of both Th1 and Th17 cell responses.

Intraocular DHODH-inhibitor PP-001 suppresses relapsing experimental uveitis and cytokine production of human lymphocytes, but not of RPE cells

BackgroundUveitis is a potentially blinding inflammatory disease of the inner eye with a high unmet need for new therapeutic interventions. Here, we wanted to investigate the suppressive effect of the intraocular application of the small molecule dihydroorotate dehydrogenase (DHODH)-inhibitor PP-001 on experimental relapsing rat uveitis and furthermore determine its effect on proliferation and cytokine secretion of human peripheral blood lymphocytes (PBL) and human retinal pigment epithelial (RPE) cells in vitro.MethodsSpontaneously relapsing uveitis was induced in rats by immunization with interphotoreceptor retinoid-binding protein (IRBP) peptide R14. PP-001 was injected intravitreally after resolution of the primary disease to investigate further relapses. Proliferation and metabolic activity of phytohemagglutinin (PHA)-stimulated human peripheral lymphocytes with and without PP-001 and cytokine secretion were determined by XTT assay and bioplex bead assay. The RPE cell line ARPE-19 as well as primary human RPE cells treated with PP-001 or anti-vascular endothelial growth factor (VEGF) antibody bevacizumab were also investigated for metabolic activity and cytokine/chemokine secretion.ResultsInjection of PP-001 into rat eyes reduced the number of relapses by 70%, from 20 relapses (57% of the rats affected) in the control group to 6 relapses (33% of the rats) in the treatment group. In human PBL cultures, PP-001 reduced the proliferation in a dose-dependent manner. The secretion of several cytokines such as IL-17, IFN-γ, and VEGF was suppressed by PP-001, as previously observed with rat T cells in the experimental autoimmune uveitis (EAU) model. In contrast, human RPE cells were not affected by PP-001, while the anti-VEGF antibody bevacizumab severely impaired the secretion of various cytokines including VEGF.ConclusionsFor the first time, intravitreal injection of PP-001 demonstrated an effective, but transient reduction of relapses in the rat EAU model. In vitro PP-001 suppressed proliferation and cytokine/chemokine secretion of human lymphocytes, while neither human RPE cell line ARPE-19 nor primary RPE cells were affected.

HTRA1 enhance signaling pathway of uveitis via modulation of the TGF-β signaling cascade

High temperature requirement protein A1 (HtrA1) is a serine protease that is mostly secreted to degrade numerous extracellular matrix proteins, They are involved in the development and progression of several pathological processes such as cancer, neurodegenerative disorders and arthritic diseases, but it also exists within cells for some partially understood. The purpose of this study was to investigate the role of HTRA1 in the uveitis, and the possible mechanisms involved. Interphotoreceptor retinoid-binding protein peptide R14 to induced uveitis in rat model. A recombinant lentiviral vector carrying HTRA1-shRNA to knockdown HTRA1 expression. ELISA to detected proinflammatory cytokines and standard molecular biological techniques were used for subcloning of HtrA1. The knockdown of HTRA1 was associated with decreased the cellularlevel expression of proinflammatory cytokine resulted in reduced cellular damage, and increased mRNA levels of TGF-β1.

Fluctuation of lysosomal phospholipase A2 in experimental autoimmune uveitis in rats

Intraocular inflammation leads to oxidative stress and may generate lipid oxidation products. The present study was conducted to elucidate the pathophysiological roles of the lysosomal phospholipase A2 (LPLA2), a phospholipid-degrading enzyme, and the production of oxidized phospholipids (oxPLs) in autoimmune uveitis using a rat model. Lewis rats were immunized with a bovine interphotoreceptor retinoid-binding protein (bIRBP) peptide with complete Freund’s adjuvant (CFA) to induce experimental autoimmune uveitis (EAU). The aqueous humor (AH) and serum were collected every week for 4 weeks from the immunized rats. The LPLA2 activity of the AH and serum was detected using liposomes consisting of 1,2-dioleoylphosphatidylglycerol/N-acetylsphingosine as the substrate under acidic conditions. Immunohistochemical analysis was performed using antibodies against LPLA2 and oxPLs. The ocular inflammation was exacerbated at 2 weeks after immunization. The LPLA2 activity in the rat AH was increased by EAU induction, and was concomitant with the extent of inflammation in the anterior chamber (AC). In contrast, the LPLA2 activity in the rat serum was not influenced by EAU induction. At 2 weeks after immunization, immunoreactivity of LPLA2 was observed in infiltrated macrophages in the AC and vitreous cavity of the EAU rats. Furthermore, immunoreactivity of oxPLs was observed in the infiltrated macrophages of EAU rat eyes. These results demonstrated that the LPLA2 activity of the AH is augmented with the inflammation in the AC. The high expression of LPLA2 and production of oxPLs are found in the infiltrated macrophages in the acute inflammation of EAU rats. The present findings suggest the connection between LPLA2 activity and oxPL metabolism in the inflammation sites in the eye.

Preventive effect of chrysin on experimental autoimmune uveitis triggered by injection of human IRBP peptide 1-20 in mice.

Uveitis is a common cause of blindness worldwide. Experimental autoimmune uveitis (EAU) is an animal model of noninfectious uveitis. Chrysin (5,7-dihydroxyflavone) is a member of the flavonoid family and has anti-inflammatory effects. We immunized C57BL/6J mice with human interphotoreceptor retinoid-binding protein peptide 1-20 to induce EAU. Chrysin was administered intragastrically at 25 mg/kg daily to the chrysin-treated mice from 3 days before immunization to 21 days after immunization. Vehicle was administered to the mice in the control group according to the same protocol. Lower clinical and histopathological scores, increased integrity of the blood-retinal barrier (BRB) and higher expression of tight junction proteins were observed in the chrysin-treated mice. Chrysin significantly decreased the proportions of Th1, Th17 and CD4+CD3+CD62L+ Th0 cells, and increased the proportion of Treg cells. Both macrophage infiltration and the expression of inducible nitric oxide synthase in the retina were efficiently inhibited by chrysin treatment. In chrysin-treated mice, the expression of interferon-γ, interleukin (IL)-17A, IL-6, IL-1β and tumor necrosis factor-α was reduced in the retina, whereas higher levels of transforming growth factor-β were detected. Furthermore, NF-κBp65 was downregulated after chrysin treatment. In conclusion, as an anti-inflammatory molecule, chrysin exerts a preventive effect on EAU by modulating the balance among helper T-cell subsets and suppressing ocular inflammation, thereby maintaining the integrity of the BRB.

Vorinostat Modulates the Imbalance of T Cell Subsets, Suppresses Macrophage Activity, and Ameliorates Experimental Autoimmune Uveoretinitis

The purpose of the study was to investigate the anti-inflammatory efficiency of vorinostat, a histone deacetylase inhibitor, in experimental autoimmune uveitis (EAU). EAU was induced in female C57BL/6J mice immunized with interphotoreceptor retinoid-binding protein peptide. Vorinostat or the control treatment, phosphate-buffered saline, was administrated orally from 3days before immunization until euthanasia at day 21 after immunization. The clinical and histopathological scores of mice were graded, and the integrity of the blood-retinal barrier was examined by Evans blue staining. T helper cell subsets were measured by flow cytometry, and the macrophage functions were evaluated with immunohistochemistry staining and immunofluorescence assays. The mRNA levels of tight junction proteins were measured by qRT-PCR. The expression levels of intraocular cytokines and transcription factors were examined by western blotting. Vorinostat relieved both clinical and histopathological manifestations of EAU in our mouse model, and the BRB integrity was maintained in vorinostat-treated mice, which had less vasculature leakage and higher mRNA and protein expressions of tight junction proteins than controls. Moreover, vorinostat repressed Th1 and Th17 cells and increased Th0 and Treg cells. Additionally, the INF-γ and IL-17A expression levels were significantly decreased, while the IL-10 level was increased by vorinostat treatment. Furthermore, due to the reduced TNF-α level, the macrophage activity was considerably inhibited in EAU mice. Finally, transcription factors, including STAT1, STAT3, and p65, were greatly suppressed by vorinostat treatment. Our data suggest that vorinostat might be a potential anti-inflammatory agent in the management of uveitis and other autoimmune inflammatory diseases.